While the barrel stamp isn't perfectly clear, I believe you have read it correctly. Details of the rifle show a strong New York influence, specifically in the single trigger, slight curve or "fish belly" in the lower butt line, walnut stock, and elongated cheekpiece. Based on those details, an educated guess on the maker would be gunsmith William F. Green who was working in Buffalo, New York, in the 1850 census and Lockport, NY, in 1855. Apparently, he worked briefly in Hamilton, Ontario, in 1857 and then moved on to Detroit, Michigan, where he appears in the 1860 census. A good number of New York gunmakers who left NY moved west to Michigan [where local rifles often look like NY rifles], supporting the likelihood of William Green being the right gunmaker. I would date your rifle to the 1850-1855 period while he was working in New York.
Shelby Gallien
